title: Ambient temperature, air pollution, and heart rate variability in an aging population.
abstract: Studies show that ambient temperature and air pollution are associated with cardiovascular disease and that they may interact to affect cardiovascular events. However, few epidemiologic studies have examined mechanisms through which ambient temperature may influence cardiovascular function. The authors examined whether temperature was associated with heart rate variability (HRV) in a Boston, Massachusetts, study population and whether such associations were modified by ambient air pollution concentrations. The population was a cohort of 694 older men examined between 2000 and 2008. The authors fitted a mixed model to examine associations between temperature and air pollution and their interactions with repeated HRV measurements, adjusting for covariates selected a priori on the basis of their previous studies. Results showed that higher ambient temperature was associated with decreases in HRV measures (standard deviation of normal-to-normal intervals, low-frequency power, and high-frequency power) during the warm season but not during the cold season. These warm-season associations were significantly greater when ambient ozone levels were higher (>22.3 ppb) but did not differ according to levels of ambient fine (≤2.5 μm) particulate matter. The authors conclude that temperature and ozone, exposures to both of which are expected to increase with climate change, might act together to worsen cardiovascular health and/or precipitate cardiovascular events via autonomic nervous system dysfunction.
authors.affiliation: Exposure, Epidemiology, and Risk Program, Harvard School of Public Health, Boston, Massachusetts 02215, USA. rencizao@yahoo.com
authors.forename: Cizao
authors.initials: C
authors.lastname: Ren
authors.forename: Marie S
authors.initials: MS
authors.lastname: O'Neill
authors.forename: Sung Kyun
authors.initials: SK
authors.lastname: Park
authors.forename: David
authors.initials: D
authors.lastname: Sparrow
authors.forename: Pantel
authors.initials: P
authors.lastname: Vokonas
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000009:adverse effects*; D001900:Boston / Q000453:epidemiology; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology; D006339:Heart Rate / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010126:Ozone / Q000633:toxicity; D012621:Seasons
chemical_list: D010126:Ozone